Modeling of thermoelectric effects in phase change memory cells

Phase change memory (PCM) is an emerging fast and non-volatile memory technology. PCM devices are based on the resistivity contrast between the amorphous (high resistivity) and crystalline (low resistivity) phases. Amorphization (Reset) is achieved by by a large and short electrical pulse which melts a small volume of material and allows fast cooling. Crystallization (Set) is achieved by heating the amorphized region above the crystallization temperature for a sufficiently long duration [1]. These devices operate at high current densities and high temperature gradients which give rise to significant thermoelectric effects observed as asymmetric heating and amorphization of the structures [2]. These effects have been observed in silicon microwires [3] and p-type SbTe [4], doped SbTe [5] and GST phase-change memory cells [6]. Numerical modeling of PCM devices has been performed using approximated analytical solutions to the electro-thermal equations and constant physical parameters [4][6].